Microphone amplifier MAX9812 + finish it yourself.

Recently there was a review on the microphone amplifier on the MAX9814.
The review caused a lot of comments, which means there is interest in the topic.
A year ago, I, too, had to strongly “smoke” this topic, because my good friend, right after I decided to run my channel on YouTube, ran into the problem of sound recording.

The fact is that ordinary computer microphones onelectret caps that are abundantly represented in computer stores, more or less tolerably work only in Skype, but are completely unsuitable for dubbing in video capture programs from the screen, which are usually used by bloggers creating videos for YouTube.
Programs like Bandicam, FastStone Captureworking with these microphones is bad. The sound is written very, very quietly. The sound level in the recordings is not enough just catastrophically and no program tricks of the situation save.
At first, my comrade struggled with this disaster on his own, tried several electret microphones from computer stores - the result was zero and turned to me - what to do?
Began to study this topic together. They exploded the Internet - prices for more or less bloggable microphones start on Ali from 3,000. There are of course cheaper, but microphones with recommendations cost about 3 thousand or more. My friend was not ready to lay out such money, because at this stage the task was simply to try to record the first video.
They began to look for more affordable options and stumbled upon Ali on the MAX9812 microphone amplifier shawl.
They ordered a shawl, but when it still fits, and the result was needed here and now.
Thus, a further search was brought to the article by Nikolay Sukhov on IXBT - Complementary Si / Ge SRPP in a preamp for an electret or a master class on Microcap-11 in the practice of audiophile.
Below is the schematic and picture from there. As an active element of Q2, the KT3102 transistor was used in all cases, and as a Q1 transistor, instead of GT310B, the KT3107, GT322, MP39B transistors were tried and showed good results without any other changes in the circuit.


I soldered to him, in a hurry, mounted installation,The amp of this circuit on KT3102 and KT3107, which immediately earned from the phantom power of the sound card available on the microphone input. All this managed to be pushed into the head of a cheap store electret microphone that he already had. Such

He was satisfied to madness! ))) Still would! So much money saved! )))
Well, I, once I became aware of such a problem, I also decided to make such a microphone option for myself. Suddenly useful? )
I bought an ordinary electret capsule,

also, canopy

He soldered the same scheme from Sukhov and put the whole thing in a piece of brass tube.

As a stand used a candlestick, lying around idle in the pantry. The result was such a glamorous microphone. A knob (windscreen) clothed to give a complete image.

Then, somewhere in a month, came with Ali shawlmicrophone amplifier MAX9812. Her phantom power from the company was already a little, you need an external one. Long thought over the design. The decision came when visiting the store Fix Price. They sell wonderful LED lamps on batteries, which have a battery compartment for 3 AA elements with an ON-OFF button and a flexible rack on which you can fix the head with a microphone.

Wiring diagram of connecting the scarfs MAX9812 with external power voltage from 3 to 5 volts and plug jack 3,5

Since the output of the microphone with amplifiersignificantly higher, that is, it makes sense to stick it not into the microphone, but into the line input of a sound card, which has better parameters than the microphone input. I do not have a linear input, so I use the microphone input.
The shawl itself has wonderfully entered a piece of tubefrom a medical syringe for 5 ml. In the rubber piston of the syringe I made a hole through which I inserted a flexible lamp strap with a tight fit and sealant! the product is ready! Inside the tube I put a rolled-up piece of paper into a ring to close the wires soldered to the board. In theory, the paper tube can close all the insides. I closed only the wires because the scarf has a miniature LED. I thought that it would glow beautifully, but it turned out that it was shining very weakly, there was no effect, so it makes sense to bring a brighter separate LED into the head, then it will turn out quite nicely, like microphones in the meeting rooms of our respected deputies. You can also put some bombs on the tip - wind protection. All this was in the plans, but, as usual, if you didn’t do it right away, you would never do it again. )

Sweet couple - MAX9812 vs Complementary Si / Ge SRPP from N. Sukhov.

- Finally, test records. The first of these was made in December 2017, when the discrete-element circuit was assembled and tested according to N. Sukhov’s article given at the beginning of the review. The recording is continuous, but consists of 7 pieces. As an element of Q2, the KT3102 transistor was used everywhere, and in place of Q1, KT3107, GT322, GT328, GT346, MP39B were sequentially soldered and, last, KT3107 was put again. No other elements of the scheme did not change, the modes were not adjusted, the recording level was not adjusted. Good results were shown by transistors 3107, GT322, MP39B. The best result, in my subjective opinion, is in transistor MP39B. He, in the end, I applied in the finished design of the microphone which I assembled in a brass tubular casing. So, listen. The beginning of the recording is “naked cap”, so the sound is very quiet, but it is
yadi.sk/d/VeduhzDA3aNiKQ
Another entry was made during the preparation of this material. So sounds the Chinese assembly MAX9812 with external power supply from three AA elements and connected to the microphone input of the laptop.
yadi.sk/d/z9ghPIk13aMfc5
And, the last one, also fresh, is purely for quick comparison of the sound of the MAX9812 and the amplifier on a discrete distribution of Sukhov. I recall the active elements in the scheme KT3102 + MP39B
yadi.sk/d/gng-ahnY3aMfcq
I hope that the information provided will be useful to someone. Good luck to all.